While electrical dipoles can be broken into separable, opposite charges, breaking a magnetic dipole does not separate its north and south poles. It results instead in two smaller dipoles. The possibility of elementary, quantum, magnetic monopoles has been explored theoretically by Dirac [1]}, but no such particle was ever found [2]}.
The concept, however, has proved useful in describing emergent quasi-particles in liquid crystals [3]}, skyrmion lattices [4]}, Bose-Einstein condensates [5]}, and in the context of the anomalous Hall effect [6]}.
The notion of a magnetic monopole is perhaps the closest to the classical intuition in a special class of frustrated binary magnets called spin ices, either crystal grown [7]}, [8]}, [9]}, [10]}, [11]}, [12]}, [13]}, [14]} or artificially fabricated at the nanoscale, the so-called “artificial spin ices" [15]}, [16]}, [17]}, [18]}, [19]}, [20]}, [21]}, [22]}, [23]}, [24]}, [25]}. These magnetic materials are made of interacting moments that can be described as binary variables arranged along the edges of a lattice. The moments are atomic in rare earth pyrochlores, and have sizes of tens or hundreds of nanometers in nanofabricated artificial spin ices.
